21211212020 has 72 divisors (see below), whose sum is σ = 47220301800. Its totient is φ = 8002209024.

The previous prime is 21211212017. The next prime is 21211212031. The reversal of 21211212020 is 2021211212.

It can be written as a sum of positive squares in 4 ways, for example, as 9515222116 + 11695989904 = 97546^2 + 108148^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21211211986 and 21211212004.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1646966 + ... + 1659794.

It is an arithmetic number, because the mean of its divisors is an integer number (655837525).

Almost surely, 2^21211212020 is an apocalyptic number.

21211212020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211212020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23610150900).

21211212020 is an abundant number, since it is smaller than the sum of its proper divisors (26009089780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21211212020 is a wasteful number, since it uses less digits than its factorization.

21211212020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13105 (or 13084 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21211212020 its reverse (2021211212), we get a palindrome (23232423232).

The spelling of 21211212020 in words is "twenty-one billion, two hundred eleven million, two hundred twelve thousand, twenty".